Method of and apparatus for distributing the charge in blast furnaces



y 1959 H. H. MEYNADIEYR 2,886,306

METHOD OF AND APPARATUS FOR DISTRIBUTING 4 Sheets-Sheet 1 v THE CHARGEIN BLAST FURNACES Filed Sept. 15. 1954 ay 2, 959 H. H; M EYNAl Dl ER2,886,306

METHOD OF AND APPARATUS FOR DISTRIBUTING THE- CHARGE IN BLAST FURNACESFiled Sept. 13. 1954 I 4 Sheets-Sheet 2 ew; 4 W.

May 12, 1959 H. H.MEYNADIER 2,386,306

METHQD OF AND APPARATUS'FOR DISTRIBUTING THE CHARGE IN BLAST FURNACESFiled'sepjz. 15. 1954 4 Sheets-Sheet s H. MEYNADIER METHOD OF ANDAPPARATUS FOR DISTRIBUTING May 12, 1959 THE CHARGE IN BLAST FURNACES 4Sheets-Sheet 4 Filed. Sept. 13, 1954 f United States Patent METHOD OFAND APPARATUS FOR DISTRIBUT- ING THE CHARGE IN BLAST FURNACES Henri H.Meynadier, Homecourt, France Application September 13, 1954, Serial No.455,733 Claims priority, application France September 16, 1953 2 Claims.(Cl. 26627) It has been found that in a blast furnace having a chargingbell, a grading action of the ore and coke takes place, the finermaterials falling almost vertically from the edge of the bell, while thecoarse materials are distributed in variable proportions betweenthecentral zone and the peripheral zone, depending on the method ofcharging and the ratio between the diameters of the throat and of thebell.

The blast furnace thus normally contains a cylindrical annular zone offine materials, which is less permeable than the other zones in thefurnace and is located immediately beneath the lower edge of the bell,between a central zone and a peripheral zone which are more permeable.Depending on the ratio between the diameters of the throat and of thebell and the speed of the air at its exit from the tuyeres, the blastfurnace has a tendency to work either more towards the axis or towardsthe walls.

In blast furnaces having large hearths, this low penneable annularcylindrical zone impedes a good distribution of the gases in the furnaceand may, in certain cases, give rise to the formation of an inactivezone along the axis of the hearth (dead man) which has been observed insome steel works.

In order to enable the gases produced in front of the tuyeres to besatisfactorily distributed as between the central zone and theperipheral zone of the blast furnace, the bell must be given a fairlylarge diameter in order that the ring formed by the fine materials belocated, in horizontal projection, at such a distance from theextremities of the tuyeres that, with a given speed of the air at theexit of said tuyeres, a portion of the flow of gas is forced into thecentral zone of the blast furnace, whilst the other portion remains inthe peripheral zone outside I the ring of fine materials and worksagainst the walls.

By reason of the relative impermeability of the ring of fine materials,the two rising currents of gas follow more or less separate'paths.

For the distribution of gases, everything goes on as if two concentricblast furnaces were actually being used, between which exchanges arerelatively diflicult.

This will explain why graphs of the results of chemical analysis of gassamples taken from the shaft at various levels and depths, plotted in adiametral direction, exhibit very irregular curves for thosecorresponding to equal contents of CO and CO as also do the isothermsplotted in the same manner.

In practice, the diameter of the charging bell being fixed once and forall in accordance with experience already acquired from previous blastfurnaces, the only way of modifying the relative magnitudes of the twocurrents of gas is to control the blower, that is, the working speed ofthe blast furnace.

Another phenomenon which has been met with very many times is that, atthe moment when the charge is introduced into theblast furnace, a dropin the pressure of the gas in the ofitakes is observed; this pressuredrop due to the fact that the ore, as it falls, constitutes animpervious annulus or screen which momentarily throttles the passage ofthe gas from the centre of the blast furnace towards the offtakes. Sincethe cross-section available for its passage is very considerablyreduced, the speed of the gas increases and the latter carries away notonly all the powdery particles from the ore but'also less fine elementswhich would have remained in the blast furnace if they had been able toreach the top of the charges by escaping from the effects of this forceddraught.

It is to recover a part of these elements that, in many blast furnaces,large intake gas conduits are provided.

The object of the present invention is to provide a method of and anapparatus for the distribution of the charge, more particularly usefulwhen the latter is composed of crushed or unciushed ore comprising afairly high proportion of fine materials, method and apparatusovercoming the disadvantages referred to above.

The great majority of equipments for distributing the charges which havebeen previously described or used in shaft furnaces, were designed fordistributing the fine elements over the whole section of the shaft orfor collecting them in the form of a cylinder more or less remote fromthe walls. These fine elementstend to fill up the spaces left freebetween the largest pieces and in- Y crease the average resistanceofiered by the charge to the passage of the gases. In addition, thecharge forms around the bell and beneath the bell, during its deliveryinto the furnace, a flared screen through which the gasm must pass.-

The method of my invention for improving the permeability of the chargein a blast furnace and facilitating its blowing, consists in dividing,during the charging operation, the annulus or screen of materialsflowing around the lower periphery of the charging bell into peripheralportions by means of radial arms of inverted trough-like or dihedralcross-section and located in a spider formation below said chargingbell, sothat at least a part of the materials of each portion aredeflected into two opposite peripheral directions; causing'the materialsof each portion to fall into the furnace when leaving said radial arms;adjusting the upper level of the charge in the furnace at a level wellbelow the level of said arms for obtaining a segregation between thesmall pieces and the big pieces of said charge during the fall of saidmaterals, said level being such that the small pieces fall and collectin radial areas substantially vertically disposed between the successiveradial arms, and the big pieces, which are more'peripherally deflectedthan the small pieces, fall and collect below said arms, whereby morepermeable sectors, (hereinafter referred to as breaches") are providedvertically in the charge through almost the full height of the shaft;providing at the bottom of the furnace a number of tuyeres twice thenumber of said arms; and setting the direction of said arms with respectto the direction of the tuyere axis, so that the breaches formed of thebig pieces of the charge are radially disposed vertically abovealternate tuyeres.

The arms having an inverted trough-like section may be eitherimmediately located below the charging bell of the furnace or arrangedaroundthe lower portion thereof, and in this last case the said arms maybe either rigidly fixed to the said bell or hingedly attached thereto.

The arms or gutters having an inverted trough-like section aresurmounted by dihedron members forming a roof above, and are arranged insuch a way that vertical breaches should be made in the charge of theshaft below, facing some of the tuyeres; in these conditions, the blastfrom these tuyeres is forced right through to the central 'zone of theblast furnace, whilst the blast from the other tuyeres provides aperipheral air blast.

In order to-avoid errors of interpretation, it should be observed thatin the mind of the inventor, it is clearly not a matter of consideringthat in the standard method of distribution, the ring of fine oredescends vertically to the bottom of the blast furnace, and that theforced draft from thetuyeres themselves strikes against it (variousresearches having shown that is front of the tuyeres, there is located azone of combustion which is more or less empty of solid material, andthat the ore itself does not fall'below a determined zone in the bushes,the temperature of-which corresponds to the point of fusion of itsconstituent parts). The object of the spider distribution of the fineelements of the ore and of the coke, is to create in the charge breacheswhich are more permeable and enable the gases injected in the zone ofcombustion to bejudiciously distributed at the level of the melting zoneand to-make it possible for them, during their upward course in theshaft, to produce a better balance of pressures and speeds between thecentral zone and the peripheral zone, and thus'to make their compositionand temperature more uniform and improving their action on the ore.

In accordance with the invention, it is quite easy to regulate the valueof the central forced draft and the peripheral draft by modifying thesection of the corresponding'tuyeres or'by fitting them with controlbushes.

Another object of my invention is to provide devices for carrying outthe method mentioned above into practice.

These and other objects will become apparent from the following detaileddescription of some embodiments of my invention with reference to theappended drawings in which:

Fig. l is a diagramamtic vertical cross-section of part of the upperportion of a blast furnace provided with a charge distributor inaccordance with the invention, the cross-section being taken along theline II of Fig. 2.

Fig. 2 is a horizontal cross-section along the line 11-11 of Fig.. 1 inrespect of the left-hand part of the figure, and along theline IIa ofFig. 1 in respect of the righthand part of the figure.

Fig. 3 is a vertical cross-section through the plane IIIIH of Fig. 1.

Fig. 4 is a diagrammatic view showing in partial development, thearrangement of the tuyeres and the members of the distributor withrespect to the charge.

Fig. 5 is an alternative form of Fig. 1 showing the case of a bell withdeflecting arms.

Fig. 6 is a detail plan view of the bell shown in Fig. 5.

Fig. 7 is a cross-section through the plane VII-VII of Fig. 6.

Fig. 8 is a horizontal half cross-section in diagrammatic form of theshaft, on which the position of the tuyeres is indicated, showing, withrespect to the latter, the position of the columns of fine material andof the breaches constituted by the coarse ore.

Fig. 9- is a view of an alternative form of the bell shown in Fig. 5with pivoted deflecting arms.

Fig. 10 is a view of a detail of Fig. 9.

Fig. 11 is a cross-section. through the plane XIXI of'Fig. 10.

In the embodiment shown in Figs. 1 to 3, which corresponds to a blastfurnace having twelve tuyeres, the

distribution device, located between the charging cone or bell a and theupper level of the charges b (Fig. 4), is constituted by a centralcylindrical member 0 (known as the cigar), retained in position andfixed to the metal I wall of the throat by the sheet steel constructionor The arms d are preferably surmounted by roofs g having the shape ofdihedrons, in the portion Where the ore falls during charging. This isin the free spaces or sectors g (Figs. 2 and 4) existing between thearms, by which the ore passes as it falls when it is discharged into thefurnace by lowering the bell a. The annulus or screen formed by the oreas it falls only shuts off the sectors situated between the arms. Thesection of these latter is calculated so as to ensure a sufficientevacuation of gastowards the peripheral part of the throat, from whichit is directed to the gas offtakes without having to pass through theore during its fall, and thus without carrying with it a proportion ofdust.

As shown in the drawing, the roofs. g are given the shape of dihedronswhich may be symmetrical, but it will be quite clear that these roofscould be replaced by inclined planes.

The number of arms of the spider member which constitute the distributoris equal to half the normal number of tuyeres of the blast furnace, theaxis of each of the arms being located exactly vertically above thetuyeres as is shown on Fig. 4, in which the arrangement of the charge band the roofs g of the arms 0! of the distributor c have been showndiagrammatically with respect to the tuyeres Nos. 1 to 6.

The finer elements of the charge which fall on the roofs slideapproximately vertically off each of the arms and are thus distributedradially; the angle ofthe upper face of the roofs and the verticaldistance between said roofs and the materials of the charge in thefurnace being such that the coarser elements of the charge falling on toone of said roofs are thrown peripherally under the neighboring arms ofthe distributor on top of the charge in th furnace.

In Fig. 4, the path followed by the fine material as it falls has beenshown in dotted lines, the path of the medium material in chain-dottedlines, while the path of the coarse material has been shown by the heavychain-lines with two dots.

The tuyeres of the row of odd numbers (for example) which are locatedimmediately below the arms of the dis-' tributor, thus blow in a sectorwherein the charge above said tuyeres contains a small proportion onlyof fineel'ements and is therefore relatively permeable, the blastissuing from said tuyeres having thus a tendency to reach the centralzone of the blast furnace (see Fig. 8).

The intermediate tuyeres (of the row of evennumbers) on the other hand,are in a sector wherein the charge above is less permeable because theproportion of fine elements in it is relatively large, and these tuyereswork closer to the walls.

In the standard method of charging, there is a uniform blowing circlewhich gives rise to a forced draught at the centre or at the peripheryover which it is not possible to exercise any substantial degree ofcontrol.

With the radial method of loading, which results in th formation ofbreaches, there is obtained at the same time a forced draught at thecentre and at the periphery, which it has" previously been attempted toobtain by means of a double system of tuyeres operating at differentpressures.

In accordance with the invention, it is thus possible to control therelative values of the blowing at the centre and at the periphery of thefurnace, and this by modifying, for example, the cross-section of thecorresponding tuyeres, or by providing them with control bushes.

It has been-indicated above that the upper part of the arms or the roofsg could be replaced by inclined surfaces; it is even possible toenvisage a certain inclination of such surfaces either towards the rightor to the .left, so as to vary the distribution of the charge if theworking of the blast furnace should so require. It is even pos sible toarrange for the angle of these deflectors to be variable at will.However, in order to adhere to principles of simple and robustconstruction, it is in general prefer.- able not to make use of suchmodifications, except very occasionally and during the period when theblast furnace 1s not in use.

Many modern blast furnaces are not provided with fabricated membersknown as cigars'under the large cone. The installation of a cylindricalmember of this kind, provided with hollow arms for evacuation of thegases, may lead to difliculties in construction.

In this case, it is still possible to produce, within a certain measure,a circuit for the gases which will answer a the same purpose, without itbeing necessary to proceed to the installation of the distributordescribed above.

It will then be suflicient, in accordance with the invention, to arrangeradial deflectors or arms at the base of the bell, of which they mayform an integral part, as shown at d in Figs. 5 to 8.

These arms d1 are much shorter than in the previous case, since it willsufiice for them to deflect peripherally the annulus or screen of fineore sliding along the surfaces of the bell at the beginning of theopening period of this latter. 1

In the case of a blast furnace using coarser ore, or scrap-iron, if itis feared that the pieces will remain caught on the upper portion of thearms of the bell, the latter may be mounted separately so as toconstitute independent arms d (see Figs. 9 to 11) suspended from thebase of the bell a, each of the arms being movable vertically about ahorizontal axis h which is itself fixed to the bell, as shown at 11 acounterweight i, adjustably mounted on the rod h integral with thepivotal axis h, retaining the arm d in its normal horizontal position.

An abnormally large lump of ore or a piece of scrapiron arriving on oneof the arms would cause the latter to pivot and would then continue itscourse without danger of becoming wedged between the arms and theseating of the bell, which would prevent the latter from closing.

The bell, provided with fixed or pivoted arms, should be guided in sucha way that each of the arms always remains in the same meridian planeimmediately above a tuyere. Finally, the arms d (Figs. 1 to 4) or d(Figs. 9 to 11) may be mounted in such a manner as to provide for thepossibility of giving them an angular displacement in the horizontalplane, the amplitude of which will be (where n is the number of tuyeresthat is to say twice the number of the arms on the bell); in this way,it will be possible, if need be, to alter the peripheral position ofeach of the columns made in the charge by the fine elements of ore froma radial plane containing a tuyerea strong tendency to accompany thecoarser elements of the ore.

It will, of course, be understood that modifications may be made to theembodiments of my invention which have just been described, inparticular by substitution of equivalent technical means, withoutthereby departing from the scope of the present invention as defined inthe fol- What I claim is:

1. In a shaft furnace having a moving bell and a fixed hopper chargingsystem at its top and an even number of blast tuyeres at the lower partof the shaft; a charging apparatus for distributing the materials of thecharge in a manner segregating the, big pieces of said materials fromthe small particles and forming in the furnace vertical radiatingcolumns having a high permeability mainly made of big pieces of saidmaterials separated by vertical columns of lower permeability mainlycomposed of small particles of said materials, each of said columnsvertically facing one of said tuyeres; said apparatus comprising radialarms equal in number to the half number of the blast tuyeres, said armsbeing made of small beams having an I section vertically disposed andsecured by their inner extremities to a hollow member centrally disposedin the top portion of the furnace, with their vertical median planecontaining the axis of alternate blast tuyeres and being securedhorizontally in the top portion of the furnace at a level lower than thelower edge of the charging hopper; spacing means located on the topportion of said shaft for vertically spacing said radial beams from theupper portion of the shaft of the furnace; brackets secured to the innersurface of said spacing means and adapted to loosely support the outerends of said beams and permit an angular displacement of said outer endsabout the axis of said shaft; said hollow member having a lowercylindrical portion, an open end at its lower extremity and a closed endat its upper extremity and being connected along said cylindricalportion with inverted trough like structures opening therein secured tothe webs of said beams and straddling the lower flanges thereof;dihedron sections secured to the upper flanges of said beams andoverlying said inverted trough-like structures, with the apices of theircross sections turned up, said dihedron sections having plane facesslanting laterally with approximately the same slope on either side ofthe median vertical planes of said beams, said dihedron sectionsradially extending from a position located adjacent the periphery ofsaid bell to a position above and at a short distance of the innerperipheral surface of the shaft; said beams being supported by saidspacing means at a distance allowing a complete segregation of the bigpieces from the fine pieces of a fresh charge during the'fall of samefrom the lower edges of said dihedron sections on top of the charge insaid shaft. 1

2. A shaft furnace having a charging apparatus as claimed in claim 1,wherein said brackets permit a total angular displacement of said outerends of said beams having a value equal to

